Household refrigerators commonly include automatic ice-makers located in the freezer compartment. A typical ice-maker provides an ice cube mold positioned to receive water from an electric valve that may open for a predetermined time to fill the mold. The water is allowed to cool until a temperature sensor attached to the ice cube mold detects a predetermined low-temperature point where ice formation is ensured. At this point, the ice is harvested from the ice cube mold by a drive mechanism and released into an ice bin positioned beneath the ice mold.
The ice harvesting mechanism may, in one example, distort the ice cube mold to remove the “cubes” by twisting one end of the flexible ice tray when the other end abuts a stop. After a brief period of time during which the motor twisting the ice mold may stall and during which the ice cubes may be ejected from the tray, the motor is reversed in direction to bring the ice tray back to its fill position for refilling. Alternatively, the cubes may be ejected by rotating an ejector comb that sweeps through the tray to remove the cubes. At the end of the ejection cycle, the tray or comb returns to a home position as may be detected by a limit switch.
An ice sensor may be provided to determine when the ice-receiving bin is full. One sensor design periodically lowers a bail arm into the ice bin after each harvesting to gauge the amount of ice in the bin. If the bail arm's descent, as determined by a limit switch, is limited by ice filling the bin to a predetermined height, harvesting is suspended.
Typical ice-makers operate to completely fill the ice bin so that ice can be available on demand by the consumer from reserves in the ice bin without concern for the relatively slow rate of ice production. The ice bin is sized to accommodate anticipated times of high ice usage; however, consumers rarely require a full bin of ice at one time, instead using small amounts of ice periodically over the space of days. With this usage pattern, a control strategy of maintaining the bin in a full configuration can lead to excess energy consumption and the creation of “stale” ice, being ice that has resided in the refrigerator for an a sufficient period of time to begin to absorb refrigerator odors that can be imparted into a drink when that ice is used.